Compressed air in the pharmaceutical industry: part 2

When it comes to compressed air, a great deal can often be achieved with just a few measures to increase efficiency and cost savings.

In the second part of this article series, Kaeser Compressors describes the key points to observe in the process of renovating an existing or planning a new compressed air system, and provide some tips on optimisation. Part 1 is available here.

Introduction

Energy costs account for the lion’s share of total compressed air supply costs. For an optimised compressed air supply produced by a new station with air-cooled compressors, the cost profile is divided as follows: commissioning and training of maintenance staff account for around just 1% of total costs; the same goes for condensate treatment. Installation expenses and the cost of controllers and process control systems come in at 7%, and procurement of treatment equipment at 5%, with that of compressor equipment at around 13%. Maintenance of compressors accounts for 3%, whilst treatment system maintenance comes in at 1%.

The largest cost block by a huge margin derives from energy expenses to supply compressors and treatment equipment, however, at 69% (Figure 1). This striking figure makes clear how energy performance is one of the most important indices for evaluating compressors.

Figure 1: Cost profile for an optimised compressed air supply produced by a new station with air-cooled compressors.

Energy efficiency considerations therefore play a central role in system planning, which always begins with a thorough analysis of the current air demand situation — for both new systems as well as renovations of existing ones. The audit can be carried out either by an external expert or the operator can take on the task internally.

When using an external expert to measure pressure and air consumption, the operation of the compressed air station and of the entire system is analysed for a period of at least 10 days using modern data logger technology (Figure 2). The data logger collects the relevant measured values and transfers them to a computer, which generates a detailed consumption diagram. This includes pressure drops, pressure and consumption fluctuations, idling behaviour, load and compressor standstill times as well as each individual compressor’s contribution in supplying the compressed air consumed.

A specialised program then calculates the optimal configuration and cost saving potential. This analysis goes beyond determining energy consumption at intervals at a certain compressed air demand; rather, it’s possible to obtain a precise picture of the specific power performance of the compressor station during its entire runtime. This means weak points in the partial-load range are identified and remedied well in advance. The overall result is a clear statement of the achievable cost savings and amortisation details.

Figure 2: The air demand can be precisely calculated and evaluated using modern measuring devices such as the ADA data loggers from Kaeser (for analysing compressed air duty cycles).

Performing analysis independently

Operators who wish to plan their own compressed air supply are advised to begin the analysis at the end of the system, i.e., with the end equipment that is consuming the compressed air, and work backwards step by step to the compressed air production itself. The first aspect to consider is the required compressed air quality and how this will be achieved.

Naturally, the compressed air quality levels required at the end equipment depend first and foremost on the needs of the individual company; the relevant requirements and classifications are defined in ISO 8573. VDMA Guideline 15930-2 provides purity class recommendations by application type and was specially developed for the pharmaceutical industry.

Pipes: material, connection, joining

The pipelines themselves are the next system component upstream of the equipment. The important criteria here are: manner of laying the pipe; material; manner of compressed air distribution throughout the company; and the method for joining the pipes to one another and to the components.

The pipeline system should be laid in as many straight lines as possible to save energy. Sharp 90° corners cause major pressure loss and can be easily replaced with generously dimensioned 90° arcs. Instead of the commonly used water shutoff units, ball valves or flap valves with full — not reduced — diameter should be used.

Since the pharmaceutical industry generally has very stringent compressed air quality requirements, pipeline material should be selected with a view to avoiding contamination. The correct joining technique is also very important. Pipeline parts should either be connected to one another by welds, adhesive or using a combination of screws and adhesive.

Leaks

Leaks in the system are the most active causes of energy waste in a company. Since they’re at work around the clock, 8760 hours per year, leaks unsurprisingly represent the most significant source of loss in the majority of systems. Studies demonstrate that between 25 and 60% of the compressed air produced is lost due to leaks, and leaks occur regularly even in carefully maintained systems. Paying extra attention to building a tight, leak-free system is therefore imperative (Figure 3).

Figure 3: The real cost of compressed air leaks.

The simplest method of locating leaks is to use an ultrasound measurement device (Figure 4), since the location of leaks can then be pinpointed during production hours. Such a device can be rented from all leading providers in the compressed air sector, if an expert is not specifically engaged to perform this task.

Figure 4: Leaks should be measured regularly, e.g., by using an ultrasonic leak detector.

Treatment and compressors

Once the focus has shifted upstream to the compressed air station itself, the compressed air treatment becomes the first area to consider. Basically every type of compressor is capable of producing the quality levels required in the pharmaceutical industry. Whether the compression process is oil-free or oil-injected makes no difference since compressed air is nothing other than the ambient air in compressed form — and ambient air always contains contaminants. This means treatment is always necessary to meet the high requirements of the pharmaceutical industry.

In most cases, a precisely coordinated configuration of compressors with different capacities turns out to be the ideal solution. This usually consists of large base load and standby machines, combined with smaller peak load machines (Figure 5). The master controller is responsible for coordinating production of the required compressed air with maximum cost efficiency. Modern master compressed air management systems not only enable real-time monitoring, but also analysis and recommendations to ensure constant optimisation.

Figure 5: For truly efficient compressor operation, a combination of base load and peak load machines is essential (for a larger image, click here).

If all of these steps are followed, the compressed air supply will not just be efficient, cost-effective and reliable, it will also be compatible with future developments.

To read Kaeser’s entire whitepaper series on compressed air in the pharmaceutical industry, visit https://bit.ly/3WWYyCs.